1. Field of the Invention
This invention relates to a semiconductor device and an electronic device by use of said device, more particularly to a semiconductor device with a structure of bipolar transistor structure and an electronic device utilizing the same.
2. Related Background Art
There have been known in the art devices having thin films through which tunnel current flows as a the emitter, such as bipolar transistor (BPT) with an MIS structure, a heterobipolar transistor (HBT) having a micro-crystal (.mu.c) or an amorphous semiconductor as the emitter, etc.
In this case, in the above-mentioned BPT with MIS structure, by utilizing the difference in the tunnel probability between electrons and positive holes, the positive holes from the base are impeded by the above-mentioned thin film, thereby effecting reduction of the base current.
However, the above-mentioned BPT with the MIS structure of the prior art, for obtaining characteristics for effecting reduction of the of the above-mentioned base current, will require a necessary minimum thickness of the above-mentioned thin film. If its thickness is too thin, the inhibition ratio of positive holes will be lowered, whereby no reduction of the base current can be effected, with the result that the direct series resistance of the emitters will be increased.
Also, in the case when the difference in transmittance of positive holes and electrons is small, inhibition of positive holes cannot be accomplished. Further, although utilization of such difference in transmittance may be applicable to an npn type transistor, it is not applicable to a pnp type transistor, which is different in junction type.
On the other hand, in HBT by use of .mu.c of the prior art, the emitter-base junction, namely the interface between the emitter by use of .mu.c-Si and the base is unstable, and in the low current region of base current, particularly recombination becomes prevailing, whereby the current amplification ratio h.sub.FE will be markedly lowered.
Also, in .mu.c-Si of the prior art, the addition of heat treatment will result in reduction of current amplification ratio h.sub.FE even at, for example, 450.degree. C. Such reduction may be considered to be caused particularly by lowering in thee band gap and the elimination of H (hydrogen) contained in .mu.c-Si, etc. because of the increased particle sic of .mu.c-Si.